Process for the recovery of precious metals.



ROBERT E. Irons-or BLOOlllINGTON, INDIANA.

PROCESS FOR THE RECOVERY 0F rmcrous METALS.

No Drawing.

To all whom'z't may concern:

Be it known that I,- ROBERTE. LYoNs, a

citizen of the United States, residing atl Bloomington, in Monroe county, State of Indiana, have invented cert-am new and useful Improvements in Processes for the Becovery of Precious Metals, of Which the following is a specification,

My invention relates broadly to a new and improved process of extracting the more negative 'electro-chemical elements and their alloys in their natural condition as found in gravel, clay or sand, or in crushed ma te'rial or concentrates, and specifically relates to the formation of an amalgam of the valuable silver; gold and platinum' metals.

. The object of my invention broadly is to produce a process whereby the precious metalsand particularly gold and platinum and their alloys in their natural state may be readily recovered without previous smelting or other treatment and the invention consists in the new and novel. features and steps" hereinafter set forth.

The process consists primarily in agitating or otherwise bringing into intimate physical and chemical contact the auriferous or platiniferous metals or alloys thereof in coated with the amalgam of the positivemetal, but it is obvious that any suitable mixed method may be used to bring the sub-.

stances into intimate physical and chemical association. This mixing forms anamalgam of the precious metals from which the pure precious metals may be separated from the residue by any approved means, this step being Well known and forming no part of the novelty of my invention. NVhile theoreticallythe amalgam of any metal electropositive to mercury may be employed, the

more positive of the metals, such as sodium or any of the light earth metals yield Specification of Letters Patent.

Patented Feb. 1 1., .1919.

Application med March20, 1913. Serial No. 755,681.

amalgams which have the disadvantage of being readily decomposed by water which 1s usually present in an operation of this character. It has been found from experiments that the best results, commercially, are obtained from the use of an amalgam of zinc or a compound amalgam of zinc afld bismuth, especially as platinum adherence for zinc amalgam.

has a strong 05 In the presence of the gold, platinum or in factany of the negativeelectro-chemical.

metals, this positive metal amalgam is brought into'contact with a substance, referably in the form of a solution, capab e of attacking the electro-chemioally positive metal or metals in the amalgam, which action appears to decompose this amalgam and permit the adherence of'the gold, platinum or, othernegative electro-chemical metal.

This decomposing'subst-ance may be either an acid which presumably forms asalt or compound with the electro-positive metal,

liberating free hydrogen, or in some cases it may be a strong alkali, preferably, slightly warmed, such as sodium hydroxid in" which case there is a liberation of a free hydrogen. The proportion of the materials may be varied within relatively Wide limits, but a one per cent.' zinc amalgam anda three per cent. sulfuric or hydrochloric acidsol'ution has been found very eflicient.

The positive metal amalgam may be prepared by mixing the elements beforebeing added to the precious metal. bearing materials or 'they may be added separately, it

being merely necessary to bring. the elements together in the presence of the precious metals and the decomposing solution.

By means of this process it is possible to amalgama'te the precious metals such as gold, even when covered by those substances which usually o'bstructthe amalgamation. These foreign coatings are usually some of the formspf sulfur, iron, arsenic, or compounds such ashydrated silicates, and their presence has heretofore rendered the extraction of such gold both difficult and expensive. The amalgam of positive metals such as zinc is not destroyed by the presence of Water. Furthermore, the more positive metal in the amalgam is attacked but slightly or not at all, except in the presence of the precious metal sothat the process is. economical, using the least possible amount of re-agents.

The amalgam of the precious meta ls thus formed is very stable. and the metals will not 'cally negative to mercury. Having thus described my inventlon what I claim as new and desire to protect by "Letters Patent is separate when the material such as sand, clay, gravel or concentrates are being tumbled, stirred, raked or mixed together,

her when the material is being passed through sluices 0r dtherriflles or tables or.

similar devices for the purpose of sep rrating the gangue and waste.

' Although. I have described my process with reference particularly to gold rand platinum, metals or alloys, it is to be understood that the process is equally applicable to silver and the rare metals electro-chemi- In the art of forming a platinum amalgam from platiniferous'material associated with gangue, the process which conamalgam, from platiniferous material asso ciated with ga'ngue, the process which consists in bringing the material into contact withmercury -zinc andsulfuric acid;

.This specification signed and witnessed this 17th day fMarch, A. 1913.

ROBERT E. LYONS.

Signed in the presence of- M. P. WINNE, MABEL J. COOPER. 

